Process of improving the electrical resistance of animal fibers



rammed Feb. 22, 1938 2,109,087

PROCESS OF IMPROVING THE ELECTRICAL RESISTANCE OF ANIMAL FIBERS Alfred Cecil Goodings, Toronto, Ontario, Canada, assignor to Dominion Silk limited, Toronto, Ontario, Canada No Drawing. Application June 12, 1936, Serial No. 84,978

12 Claims. (Cl. 28-58) This invention relates, especially to the treatremaining in the chamber removed through the ment of threads or yarns of silk or wool used in outlet, as, for example, by means of an exhaust covering electrical wires and cables. In such fan. coverings high resistance to the passage of elec- The silk is then dried out in the heated chamtric currents is of great importance in order her to get rid of entrained steam, allowed to cool 5 that a maximum of resistance may be obtained and then removed. with as small an amount of material as pos- Throughout the process the pressure inside the sible. chamber will be maintained substantially at that Animal fibers, such as natural silk and wool, of the atmosphere, though higher and lower presare comparatively good insulators, but it has sures may be used. It has previously been stated 10 been found that their natural resistance can be that the steam should be dry. By dry" is very greatly increased by subjecting the material meant that it should be free of any entrained to an acid treatment which removes a considermoisture likely to be d p s d on the material able part of the natural ionizable salts contained being treated.

therein and which are detrimental to its elec- Some results of the treatment of materials 15 trical resistance. Such acid treatment processes which have not been pre sub e to an are well known in the art and I make no claim acid treatment are as follows: In all cases the to the same. electrical resistance figures are for lengths I have, however, discovered that the electrical of ya under conditions of 85% relative humidresistance of such materials can also be greatly 'ity at a temperature of 100 F, 20 increased by treating it with dry steam as hereinafter described; While the steam treatment Electrical resistance has a very marked effect in increasing the re- Material I hiresistance of material which has not undergone any Before steam After steam gimme 5 treatment to remove the natural salts, its greattreatment 03mm est value lies in the treatment of material-which has undergone an acid treatment or other treat- W l a gg a flg Time 17 merit for the above P rpose. si1i bi2iihili1 44.5 040 13% I The essential feature of the steam treatment is W must be earned out under such condl' Tussah silk previously acid treated showed the 30 tions that condensation of water .on the material following results. is prevented.

The process may be carried out in a closable Y E l m chamber adapted to be heated and provided with ac ma rem Me I in an inlet for the introduction of steam and an Mamii B s ifince 35 elore steam Alter steam outlet for air or steam. Automatic means will treatment treatment be provided for controlling the heating means that any desn'ed temperature may be main- Tussah silk (puri- Kilomegohma Kilomegohms Timer tained in the chamber. fled) 2400 00 The following is a detailed description of the procedure in treating silk yarn, either true silk From the above the tremendous increase in the or wild silk such as tussah. electrical resistance of silk and wool, either acid The chamber is heated to approximately 150 F., treated or not, and due to my steam treatment the silk in skeins placed therein in their norwill be evident. 45

. mal air-dry condition and the chamber closed. While I do not desire to limit myself to any The temperature is then raised to a point above particular process of treating the silk or wool to the boiling point of water, sayv 220 F. Steam is reduce its content of objectionable salts before then allowed to enter and the temperature of apsteam treating, the following treatment has proximately 220 F. maintained during the treatproven satisfactory: 5o

ment. Under such conditions all condensation of A bath is made up containing'a 1% aqueous water on the silk is entirely prevented. The flow solution of acetic acid, the volume of liquid being of steam is continued till all air is forced out of approximately 1 gallon per pound of silk to be the chamber and preferably for some time theretreated and the temperature approximately F. after. About twenty minutes'is usually suflicient. The silk in the form of skeins is immersed in r a The supply of steam is then cut ed and any stem the solution and soaked, with gentle agitation for about 20 minutes. The skeins are then removed, drained and thoroughly rinsed with water until liquid squeezed out shows only a slightly acid reaction (pI-I about 5). The material is then dried.

Other acids, such as hydrochloric, may also be employed. So also any method may be employed, other than the acid treatment for removing ionizable impurities from the silk or wool.

What I claim as my invention is:

1. A process of treating animal fibers to increase their electrical resistance which consists in subjecting the material to the action of an atmosphere of dry steam.

2. A process of treating animal fibers to increase their electrical resistance'which consists in heating the material to a temperature above the boiling point of water and thereafter'subjecting the material to the action of an atmosphere of dry steam.

3; A process of treating animal fibers to increase their electrical resistance which consists in heating the material to a temperature above the boiling point. of water and thereafter subjecting the material to the action of an atmosphere of dry steam, removing the steam and thereafter for a short time maintaining the temperature of the material above the boiling point of water.

4. A process of treating animal fibers to increase their electrical resistance which consists in treating the material to remove at least part of any natural salts contained therein which are detrimental-to-the insulating properties of the material and thereafter subjecting the material .to the action of an atmosphere of dry steam.

5. A process of treating animal fibers to increase their electrical resistance which consists in treating the material to remove at least part of any natural salts contained therein which arev detrimental to the insulating properties of the material and thereafter subjecting the material therein which are detrimental to the insulating properties oi the material and thereafter subjecting the material to the action of an atmosphere of dry steam.

7. A process of treating animal fibers to increase their electrical resistance which consists in treating the material with dilute acid to remove at least part of any naturalsalts contained therein which are detrimental to the insulating properties of the material and thereafter subjecting the material to the action of an atmosphere of dry steam under conditions inhibiting the condensation f steam on the material.

8. A process ofitreating animal fibers to increase their elect cal resistance which consists in treating the material to remove at least part of any natural salts contained therein which are detrimental to the insulating properties of the material, heating the material; thereafter subjecting the material to the action of an atmosphere of dry steam; removing the steam and thereafter for a short time maintaining the temperature oi the material above the boiling point of water.

9. A process of treating natural silk yarns to increase their electrical resistance which consists in subjecting the material to the action of an atmosphere of dry steam.

10. A process of treating wool yarns to increase their electrical resistance which consists in subjecting the material to the action of an atmosphere of dry steam.

11. A process of treating natural silk yarns to increase their electrical resistance which consists in treating the material to remove at least part of any natural salts contained therein which are detrimental to the insulating properties of the material, and thereafter subjecting the material to the action of an atmosphere of dry steam.

12. A process of treating wool yarns to in-.

crease their electrical resistance which consists in treating the material to remove at least part of any natural salts contained therein which are detrimental tothe insulating properties of the material, and thereafter subjecting the material to the action of an atmosphere of dry steam.

a. c. GOODINGQ: 

